1. Field of the Invention
The present invention relates to a piston coupling mechanism for a swash plate type compressor. More particularly, it relates to an arrangement for coupling the pistons to the swash plate in a variable capacity compressor.
2. Description of the Related Art
A swash plate type compressor has a rotary plate which is pivotally supported on a drive shaft and rotates integrally with the drive shaft. A swash plate is provided on the rotary plate to be rotatable relative thereto, and is coupled to a plurality of single head pistons by corresponding piston rods. Further, a swash plate baffle mechanism prevents the swash plate from turning while the rotary plate is rotating to maintain the accurate reciprocation of the piston.
To simplify the structure of the above-described swash plate type compressor, a compressor as disclosed in Japanese Unexamined Patent Publication No. 60-175783 has been proposed. In the disclosed compressor, each piston includes hemispherical shoes 100 that are fitted in a spherical recess 103 at a neck 102 of the piston 101 to be supported there, as shown in FIG. 12. The flat end surfaces of the shoes 100 contact a swash plate 104. With the supporting structure of the shoes 100, the piston 101 can be reciprocated in the axial direction in accordance with the swinging motion of the swash plate 104. This swash plate type compressor therefore does not need the rotary plate and the swash plate baffle mechanism, thus significantly simplifying the mechanism.
As the swash plate 104 is turned, however, a side load is applied to the piston 101 from the swash plate 104 via the shoes 100. The load then causes a one-sided abutting between the piston 101 and a cylinder 105, which may wear out the portion where the piston 101 abute against the cylinder 105 or may cause that portion to be burnt.